I think governments see Bitcoin as a problem in terms of money laundering, drugs, tax evasion, etc. For this, they will try to regulate it more closely. They will not try to downright attack Bitcoin for these offenses. What they will attack it for is when they realize that those offenses are just a distraction… for the real power of Bitcoin is that it will increasingly compete with government fiat currency. Bitcoin will pull in more and more business and incrementally the actors using it will discover less and less need for dollars or euros or yen. This happens gradually. At some point, however, the government will realize that this made-up magic internet money is wresting power away from their anointed currencies and they will then come down hard. When will this happen? I have no idea, but I imagine it will be too late, because it probably already is.